Example: Pascal's Triangle using 2D Array in Java

// Pascal's Triangle using 2D Array
import java.util.Scanner;

// Main class containing the entry point of the program
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // Step 1: Get the number of rows from the user
        System.out.print("Enter the number of rows for Pascal's Triangle: ");
        int numRows = scanner.nextInt();

        // Step 2: Declare and initialize a 2D array (jagged array for varying row lengths)
        int[][] triangle = new int[numRows][];

        // Step 3: Iterate through each row to populate the triangle
        for (int i = 0; i < numRows; i++) {
            // Each row 'i' has 'i + 1' elements
            triangle[i] = new int[i + 1];

            // The first and last elements of each row are always 1
            triangle[i][0] = 1;
            triangle[i][i] = 1;

            // Step 4: Calculate the intermediate elements for rows > 1
            for (int j = 1; j < i; j++) {
                triangle[i][j] = triangle[i - 1][j - 1] + triangle[i - 1][j];
            }
        }

        // Step 5: Print the Pascal's Triangle
        System.out.println("\nPascal's Triangle (" + numRows + " rows):");
        for (int i = 0; i < numRows; i++) {
            // Add leading spaces for proper alignment
            for (int k = 0; k < numRows - i - 1; k++) {
                System.out.print(" ");
            }
            for (int j = 0; j <= i; j++) {
                System.out.print(triangle[i][j] + " ");
            }
            System.out.println();
        }

        scanner.close();
    }
}